Oracle, the spinal blades are not an item you can trade for, it has to be crafted. You first need the 4 different blueprints. I know we have some in the guild bank and if not, let me know as I have some extra as well. After you put those in the mystic forge, then you can start building the actual backpiece. Each step requires some amount of materials and a varying amount of blade shards. To get to the final step (ascended) of the backpiece you need a total of 1,000 blade shards (spent throughout the process as a total amount). The one problem may be the gift of blades that is required to make the asceneded version and the recipe was only available from some of the collectors. I'm not sure if that recipe is still available. You could still make the rare version of the backpiece but not the ascended if you don't have the gift of blades recipe.